Assume that a gaining stream exists in physical connection with groundwater in an unconfined aquifer. Assume that several contour lines of equal head cross the stream and intercept it. True or False: Since the stream is gaining, the contour lines of equal head will increase in value as the stream is approached at right angles from a distance .

True: Since the stream is gaining, it means that the groundwater is flowing into the stream. In an unconfined aquifer, the water table represents the height of the groundwater, and contour lines of equal head represent points of equal elevation (or head) above a reference point.

When several contour lines of equal head intersect a stream, it means that these points along the stream have equal elevations above the reference point. As the stream is approached at right angles from a distance, the contour lines of equal head will increase in value. This is because the groundwater is flowing into the stream, causing the water table (and hence the head) to rise as it gets closer to the stream.

To determine the direction and magnitude of groundwater flow, the method of streamlines and equipotential lines can be used. Streamlines represent the direction of groundwater flow, while equipotential lines represent points with equal head values. The intersection of these lines indicates the direction and rate of groundwater movement.